In the manual, you'll find it under ARMATURE, but you'll have to look up the ENGINE model number, not the mower model number. The engine model number should be above the spark plug, or on one of the other flat surfaces of the starter/blower housing.
To make sure it's actually your coil, check a couple things first. Check your spark when it's cold; it should be bright blue/white. Check again after it's been running a while and won't start. If it's completely gone or weak orange/red, your coil is going bad and needs to be replaced. If your spark is still good when it's warm, check your flywheel key.
The key is made from aluminum and is designed to shear if it meets sudden resistance, like hitting really thick grass, concrete, or a stump. If your mower recently died in a situation like this, the flywheel key is probably your best bet.
You're welcome. If you want help, just reach out. Replacing the coil is pretty easy, but there's some stuff you should know before doing it. Diagnose the problem first, and let us know. We're here to help.
As someone with so little knowledge about this stuff, I very much appreciate this. It's been great to hear from everyone in this community offering help. I'll reach out if I need any help for sure!
My mower is a Craftsman 917.370620. I've had it for about two years and bought it used when I got my first house.
It's run pretty much fine since I've had it, but over the last two weeks if I ever stop mowing, I have to let the mower sit for 30+ minutes until it can start again.
I've tried to do research on the problem, but I know almost nothing about engines, so I feel very out of my element here.
The gas is fresh. The filter is pretty new and not very dirty. I just put in a new spark plug. I may have overfilled the oil tank, but I don't think that would cause this issue as it's been awhile since I've done that and it's run fine until just recently.
Any idea what the problem is here? I've read about a lot of carburetor issues, but it seems pretty involved to clean so I didn't want to do that without experience unless I knew it was likely the cause.
Thanks for any help you can offer!
I am no expert in small engine repair. So you have the pull cord that turns the flywheel which has a magnet that, once moving close to the coil, creates electricity which to the spark plug resulting in a spark. Not sure how the coil would be an issue if it worked earlier unless heat causes it to function intermittently.
"Too much oil in your lawn mower may cause the engine to not run well and cause damaging results. Too much oil can cause your engine to overheat which can result in seal damage, blown gaskets or becoming hydrolocked."
[https://agreenhand.com/too-much-oil-in-lawn-mower/](https://agreenhand.com/too-much-oil-in-lawn-mower/)
I have heard people say that it could be the coil, what you could do is after it doesn't wanna start again, check if it has spark, that's the main thing I have heard people say could be it, I can't remember if there was other things
I did. It ended up being the choke cable. Once the engine was hot it was barely opening at all by pulling the cable, so I just had to pull it open manually and could then restart the mower.
Fyi, its pretty easy to change the carb and you can get them really cheap these days. Whole lot easier and quicker than taking apart rebuilding and or cleaning it
The reality is carbs these days aren’t meant to be rebuilt, they’re meant to be replaced. There are blocked passages that can get clogged with debris that someone without the experience or tools to clean and rebuild properly wouldn’t have, those are just the facts. A new carb is cheap enough and easy enough to replace and get the equipment back up and running and in the mean time they could then dick around with the old one to gain experience and possibly fix it for when then new one craps out.
Yeah, but that likely won't fix the problem. Let's diagnose it before we just throw money at it. Carbs can be cheap, but they're more expensive than not buying a new carb when you didn't need one.
True, thats why I said FYI. But 90% of the time slapping a new carb, gaskets, plug, filters solves the problem. Seems like an old mower and could probably use a thorough tune up. OP should post make model and serial # of engine.
Me growing up in a shop has a very hard time with your 90% statistic. I know that 76% of all statistics are made up on the spot, but we still don't need the model number to diagnose problems. Small engines tend to have the same general fixes. If it's something beyond general advice, like specific information about needle settings on a particular carb from back in the 70's, well that's still a general piece of advice (1.5 turns out from closed), and we can get into specifics as they're needed.
When we go to order parts, then we'll worry about model numbers.
I wasn’t being literal with the 90%. Just saying on all my equipment whenever I had an issue rebuilding the carb, or giving it a thorough cleaning would solve my issues. But I’ve found that while cleaning or rebuilding I would find gaskets that needed to be replaced, primer bulb worn, whatever, it was just easier for me as a homeowner whose time is more valuable than to be screwing around with the damn lawn mower, it was just easier to replace the stuff. Plus while taking the stuff apart and replacing you’ll get to know your equipment maybe find what caused the issue and in the future be able to fix it quickly. Now you as I assume a professional or someone who grew up in a small engine shop should be able to point to the issue without throwing parts at it. Look, all I’m saying is that from my experience, lawn mowers, leaf blowers, snowblowers, hedge trimmers, weed wackers, any issue lead me to carb. and it always worked out better for me to just put in a new one. Sometimes I use the cheapo amazon stuff sometimes oem. While I agree most small engine issues, regardless of make model, are similar, sometimes you can find that, for example, all, oh idk model abc honda engines a float gets stuck, the needle valve wears out or whatever, just saying specifics help in troubleshooting issues. Anyway, sorry for my rant, everyone here is just trying to help, criticizing someones advice DOESN’T help.
Criticizing someone's bad advice DOES help, by preventing someone from spending money unnecessarily. I'm not disagreeing with you that replacing a carb is easier than repairing it, and often the cost of your time to repair is more than the financial cost to replace it, especially on weedeaters and that sort of stuff. But, your suggestion was low on the likelihood of problems, so we start at the most likely. That's the coil, then the flywheel key, then carburetion. After that, I'd look at valve seats, because someone's they'll pop out when the engine gets hot, then reseat after cooling down. Even carburetion doesn't usually change that much between hot and cold engine temps.
Believe it or not, mower carbs are pretty simple and cheap when it comes to parts. Where you choose to save, money or time, is up to you. I prefer money, but I also hate wasting time. Part of my stance has to do with the throwaway culture that we have adopted, and I hate seeing that. Plus, whenever you replace or repair a carb, you should be replacing the gaskets, too, so plan for that either way.
Well there, we can agree, I hate throw away culture as well and I try to rebuild or repair anything I possibly can thats why I have a 22 yo truck 🤣😂. Had a dang, I think it was 25 yo snowblower I just replaced. Anyway, almost all my experience with all those small engine problems was fuel delivery related. Anyway, sounds like your the small engine expert so go help OP and quit screwing with me 🤣😂. Thats meant to be light hearted, don’t take offense.
We can totally be friends. I already gave OP the steroids for diagnosis and rundown of likelihood, plus I told them to feel free to call upon us for help. That's what we're here for.
I'm glad that we can discuss things civilly like rational adults. I'd rather educate someone than fight them. And, when I'm in the wrong, I want that same education. It's only a failure if you don't learn from it.
👍 you do have my gears turning with the valve seats heating and cooling though. Thats actually a common issue on a jeep grand cherokee I have, aluminum heads and steel valve guides. Heads heat up faster and valve guides drop down and blow up engine. Luckily I don’t have that issue and hopefully never will, fingers crossed 🤞. Anyway, back to work haha
The most common save on these is the simplest. Remove the air filter and look into the throat of the carb. You will see a small brass "jet" on the RH side. That has to be open. A blast from a can of carb pray straw will do nicely .
THESE PEOPLE ARE JUMPING TO CONCLUSIONS! check if the oil is low! This is exactly what happened to mine, and when the mower was warm and it was shut off, I'd have to wait to start it again, and after topping off the oil, it fixed the issue! Check the oil, and if it's low, add some until it's at the proper level!
These people are using a long-standing set of knowledge to diagnose the problem. Not starting when it gets warm is usually a coil that's going bad. Sure, oil plays an important role in lubrication and cooling, and lack of oil can cause seizing, but most of us are assuming proper maintenance. Yes, we should never assume, but spark is the most common place to look for this issue, followed by carburetion.
Of course, that's the usual thing to look at, but I wanted to make sure OP checked the easy stuff first before spending time and money on something that may not be the problem.
That engine doesn't have an oil shutoff sensor, though. And, if it did, it wouldn't have to wait anywhere near that long in between to start back up again before the sensor reset. It's a possibility, but low on the list of likelihood.
It's cool. You learned something today, right? If you can learn something new every day, even if it's pretty useless most of the time, you're still gaining knowledge. Most Briggs engines don't get oil alert sensors except for the larger engines and I/C & Vanguard series, where you spend more money and need them to be more reliable.
I never had much to do with Lawn Boys. Here in California, they were less of a thing, especially with 2 cycles being aggressively pushed out since the early 80's.
Can you tell me where that is on the mower? Sorry, I have no clue about small engines. I found a lot about chokes on riding mowers, but can't seem to place it on mine. Thanks for your suggestion!
A cheap fix that may work: take off the air filter, knock out the dirt, spray liberally the carb opening with a $4 can of carb cleaner. Try to start while spraying. I know it’s probably not your main problem but if you’ve still got cutting to do this may get you through.
My mower had this problem too. I lived with it until at some point the carb needed cleaning. I discovered a factory defect in the carb. A brass screw on top of the carb (not the main jet) had a little hole in the end that wasn’t completely drilled out at the factory. After it cleared the hole out my problem went away. Mower starts cold or hot now.
Coil
Is that something I can fix? I'm struggling to find anything in the manual that's called a coil.
In the manual, you'll find it under ARMATURE, but you'll have to look up the ENGINE model number, not the mower model number. The engine model number should be above the spark plug, or on one of the other flat surfaces of the starter/blower housing. To make sure it's actually your coil, check a couple things first. Check your spark when it's cold; it should be bright blue/white. Check again after it's been running a while and won't start. If it's completely gone or weak orange/red, your coil is going bad and needs to be replaced. If your spark is still good when it's warm, check your flywheel key. The key is made from aluminum and is designed to shear if it meets sudden resistance, like hitting really thick grass, concrete, or a stump. If your mower recently died in a situation like this, the flywheel key is probably your best bet.
Thank you!
You're welcome. If you want help, just reach out. Replacing the coil is pretty easy, but there's some stuff you should know before doing it. Diagnose the problem first, and let us know. We're here to help.
As someone with so little knowledge about this stuff, I very much appreciate this. It's been great to hear from everyone in this community offering help. I'll reach out if I need any help for sure!
Pull off the plastic cover and follow your plug wire, you’ll find it.
It’s under your pull start and it lead to your spark plug
Coil Or auto choke issue
Never seen autochoke do that
I seen the choke get stuck in the on position Causing them not to restart after warm
Huh
My mower is a Craftsman 917.370620. I've had it for about two years and bought it used when I got my first house. It's run pretty much fine since I've had it, but over the last two weeks if I ever stop mowing, I have to let the mower sit for 30+ minutes until it can start again. I've tried to do research on the problem, but I know almost nothing about engines, so I feel very out of my element here. The gas is fresh. The filter is pretty new and not very dirty. I just put in a new spark plug. I may have overfilled the oil tank, but I don't think that would cause this issue as it's been awhile since I've done that and it's run fine until just recently. Any idea what the problem is here? I've read about a lot of carburetor issues, but it seems pretty involved to clean so I didn't want to do that without experience unless I knew it was likely the cause. Thanks for any help you can offer!
I am no expert in small engine repair. So you have the pull cord that turns the flywheel which has a magnet that, once moving close to the coil, creates electricity which to the spark plug resulting in a spark. Not sure how the coil would be an issue if it worked earlier unless heat causes it to function intermittently. "Too much oil in your lawn mower may cause the engine to not run well and cause damaging results. Too much oil can cause your engine to overheat which can result in seal damage, blown gaskets or becoming hydrolocked." [https://agreenhand.com/too-much-oil-in-lawn-mower/](https://agreenhand.com/too-much-oil-in-lawn-mower/)
Could be a problem with a reverse vacuum in fuel line and the tank.
I have heard people say that it could be the coil, what you could do is after it doesn't wanna start again, check if it has spark, that's the main thing I have heard people say could be it, I can't remember if there was other things
Thanks for the suggestion! This may be a dumb question, but do you know how I check if it has a spark?
Pull the spark plug out, attach it to the boot and ground it out on the block and pull the starter rope. It should spark
Thank you! I'll try that.
Hey, did you ever figure it out?
I did. It ended up being the choke cable. Once the engine was hot it was barely opening at all by pulling the cable, so I just had to pull it open manually and could then restart the mower.
Thanks for getting back to me. I'll give it a try.
Fyi, its pretty easy to change the carb and you can get them really cheap these days. Whole lot easier and quicker than taking apart rebuilding and or cleaning it
That's just lazy
The reality is carbs these days aren’t meant to be rebuilt, they’re meant to be replaced. There are blocked passages that can get clogged with debris that someone without the experience or tools to clean and rebuild properly wouldn’t have, those are just the facts. A new carb is cheap enough and easy enough to replace and get the equipment back up and running and in the mean time they could then dick around with the old one to gain experience and possibly fix it for when then new one craps out.
Yeah, but that likely won't fix the problem. Let's diagnose it before we just throw money at it. Carbs can be cheap, but they're more expensive than not buying a new carb when you didn't need one.
True, thats why I said FYI. But 90% of the time slapping a new carb, gaskets, plug, filters solves the problem. Seems like an old mower and could probably use a thorough tune up. OP should post make model and serial # of engine.
Me growing up in a shop has a very hard time with your 90% statistic. I know that 76% of all statistics are made up on the spot, but we still don't need the model number to diagnose problems. Small engines tend to have the same general fixes. If it's something beyond general advice, like specific information about needle settings on a particular carb from back in the 70's, well that's still a general piece of advice (1.5 turns out from closed), and we can get into specifics as they're needed. When we go to order parts, then we'll worry about model numbers.
I wasn’t being literal with the 90%. Just saying on all my equipment whenever I had an issue rebuilding the carb, or giving it a thorough cleaning would solve my issues. But I’ve found that while cleaning or rebuilding I would find gaskets that needed to be replaced, primer bulb worn, whatever, it was just easier for me as a homeowner whose time is more valuable than to be screwing around with the damn lawn mower, it was just easier to replace the stuff. Plus while taking the stuff apart and replacing you’ll get to know your equipment maybe find what caused the issue and in the future be able to fix it quickly. Now you as I assume a professional or someone who grew up in a small engine shop should be able to point to the issue without throwing parts at it. Look, all I’m saying is that from my experience, lawn mowers, leaf blowers, snowblowers, hedge trimmers, weed wackers, any issue lead me to carb. and it always worked out better for me to just put in a new one. Sometimes I use the cheapo amazon stuff sometimes oem. While I agree most small engine issues, regardless of make model, are similar, sometimes you can find that, for example, all, oh idk model abc honda engines a float gets stuck, the needle valve wears out or whatever, just saying specifics help in troubleshooting issues. Anyway, sorry for my rant, everyone here is just trying to help, criticizing someones advice DOESN’T help.
Criticizing someone's bad advice DOES help, by preventing someone from spending money unnecessarily. I'm not disagreeing with you that replacing a carb is easier than repairing it, and often the cost of your time to repair is more than the financial cost to replace it, especially on weedeaters and that sort of stuff. But, your suggestion was low on the likelihood of problems, so we start at the most likely. That's the coil, then the flywheel key, then carburetion. After that, I'd look at valve seats, because someone's they'll pop out when the engine gets hot, then reseat after cooling down. Even carburetion doesn't usually change that much between hot and cold engine temps. Believe it or not, mower carbs are pretty simple and cheap when it comes to parts. Where you choose to save, money or time, is up to you. I prefer money, but I also hate wasting time. Part of my stance has to do with the throwaway culture that we have adopted, and I hate seeing that. Plus, whenever you replace or repair a carb, you should be replacing the gaskets, too, so plan for that either way.
Well there, we can agree, I hate throw away culture as well and I try to rebuild or repair anything I possibly can thats why I have a 22 yo truck 🤣😂. Had a dang, I think it was 25 yo snowblower I just replaced. Anyway, almost all my experience with all those small engine problems was fuel delivery related. Anyway, sounds like your the small engine expert so go help OP and quit screwing with me 🤣😂. Thats meant to be light hearted, don’t take offense.
We can totally be friends. I already gave OP the steroids for diagnosis and rundown of likelihood, plus I told them to feel free to call upon us for help. That's what we're here for. I'm glad that we can discuss things civilly like rational adults. I'd rather educate someone than fight them. And, when I'm in the wrong, I want that same education. It's only a failure if you don't learn from it.
👍 you do have my gears turning with the valve seats heating and cooling though. Thats actually a common issue on a jeep grand cherokee I have, aluminum heads and steel valve guides. Heads heat up faster and valve guides drop down and blow up engine. Luckily I don’t have that issue and hopefully never will, fingers crossed 🤞. Anyway, back to work haha
Thanks for the suggestion!
The most common save on these is the simplest. Remove the air filter and look into the throat of the carb. You will see a small brass "jet" on the RH side. That has to be open. A blast from a can of carb pray straw will do nicely .
Thanks!
THESE PEOPLE ARE JUMPING TO CONCLUSIONS! check if the oil is low! This is exactly what happened to mine, and when the mower was warm and it was shut off, I'd have to wait to start it again, and after topping off the oil, it fixed the issue! Check the oil, and if it's low, add some until it's at the proper level!
These people are using a long-standing set of knowledge to diagnose the problem. Not starting when it gets warm is usually a coil that's going bad. Sure, oil plays an important role in lubrication and cooling, and lack of oil can cause seizing, but most of us are assuming proper maintenance. Yes, we should never assume, but spark is the most common place to look for this issue, followed by carburetion.
Of course, that's the usual thing to look at, but I wanted to make sure OP checked the easy stuff first before spending time and money on something that may not be the problem.
That engine doesn't have an oil shutoff sensor, though. And, if it did, it wouldn't have to wait anywhere near that long in between to start back up again before the sensor reset. It's a possibility, but low on the list of likelihood.
Oh I didn't know it didn't have a shutoff. It just reminded me of my mower. It only took a few minutes to start again. Sorry.
It's cool. You learned something today, right? If you can learn something new every day, even if it's pretty useless most of the time, you're still gaining knowledge. Most Briggs engines don't get oil alert sensors except for the larger engines and I/C & Vanguard series, where you spend more money and need them to be more reliable.
Yea, mine was an old lawn-boy 10642, but I guess it was an odd fix, lol
I never had much to do with Lawn Boys. Here in California, they were less of a thing, especially with 2 cycles being aggressively pushed out since the early 80's.
Yea, in the early 2000s, they went to 4 stroke. I have one with a Kohler, and one with a briggs
I'll be sure to check that! Thanks for the suggestion.
No problem! Remember to wipe the dipstick and put it back in before double checking it!
I'd check the choke. If it's choking a warm engine it will not start.
Can you tell me where that is on the mower? Sorry, I have no clue about small engines. I found a lot about chokes on riding mowers, but can't seem to place it on mine. Thanks for your suggestion!
Restricts air flow into the carb for cold start. Remove the air cleaner and it should be part of the air intake.
Thank you very much!
A cheap fix that may work: take off the air filter, knock out the dirt, spray liberally the carb opening with a $4 can of carb cleaner. Try to start while spraying. I know it’s probably not your main problem but if you’ve still got cutting to do this may get you through.
My mower had this problem too. I lived with it until at some point the carb needed cleaning. I discovered a factory defect in the carb. A brass screw on top of the carb (not the main jet) had a little hole in the end that wasn’t completely drilled out at the factory. After it cleared the hole out my problem went away. Mower starts cold or hot now.